Corrosion-resisting thermostat metal



Feb. 15, 1949. p; CHACE 2,461,5l8

4 CORROSION-RESISTING THRMOSTAT METAL I Filed March 29, 1944 /|RON, NICKEL, CHROMIUM.

W/fl//// I IRON, CHROMIUM Patented Feb. 15, 1949 &461.518 CORROSION-RESISTIN G THERMOSTAT METAL v Paul G. Chace, Attleboro Falls, Mass., assixnor to Metal Mass., a. corporation of Application March 29, 1944, Serial No. 528.614

i s Clalms. (Cl.29-195.5)

This invention relates to composite metal elements and particularly to bimetallic elements which are corrosion resisting.

This application is a continuation-in-part of my copending application Serial Number 399398, filed June 23, 1941, now Patent 2,366,178, issued January 2, 1945.

Among the several objects of the present invention are the provision of a composite thermostat metal which is corrosion resisting, which has an improved bond, and which has a long life when Operating in corrosive atmospheres and mediums; the provision of composite thermostat metal of the class described which has both good hot-rolling and cold-rolling properties; and the provision of composite thermostat metal of the type indicated which is relatively simple and economicai to manufacture. Other objects will be in part obvious and in part pointed out hereinafter. i

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, and features of composition, which will be exemplifled in the products hereinafter described, 'and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is illustrated one of various possible embodiments of the invention,

The single figure is a representation of a bimetallic element showing a strip of iron chromium alloy fused throughout its length to a similar strip of iron nickel chromium alloy. Many of the thermostatic elements commonly in use are subject to corrosion when used in the presence of moisture in 'places such as steam radiators, relief valves, or water mixing valves, or in other installations where corrosion-promoting fluids or atmospheres come in contact with the thermostat metal. As a result, such elements frequently need replacing, and inasmuch as corrosion tends to reduce their activity and life, such corrosion may set up, unknown to the user, dangerous conditions which might result in loss of life or injury. To avoid this corrosion of the composite metal element, it has sometimes been customary in the past to treat the thermostat metal surface to make it less subject to corrosion, as by plating it with a corrosion-'resisting material, such as caclmium, tin, zinc, lead, or chromium. This. however, has the disadvantage that the plating increases the cost materially and does not assure satisfactory life for the thermostatic element. Furthermore, such plating is not entirely satisfactory since an electro-voltaic potential may be set up which produces pitting and eatlng away of the protective metal. a

s & Controls Corporation, Attleboro,

Massachusetts 2 It has sometimes been the practice in the past to make a composite metallic element from an iron alloy having a high chromium content. and a metal alloy having a higher coefllcient of ex- 'pansion The metal used for the high coemcient of expanslon side has been one of the brasses. The mechanical properties of these brasses have presented manufacturing difliculties, which in many instances have prevented the manufacture of an adequate and satisfactory composite metal. For example, the cold-working properties of brass are so diflerent from those of the chromium iron alloy that it has been difflcult to satisfactorily cold-work the metal after it has been put together to form athermostat bimetal. Moreover, it is highly advantageous in the manufacture of bimetal to hot-roll the material down from its thick ingot size to 'an intermediate stage. The brasses are not adapted to this, since their hot-rolling temperatures difler too much from that of the chromium iron alloy. The manufacture of the brass-chrome iron bimetals has therefore been a relatively expensive process compared to the manutacture of bimetal in accordance with the present invention. The ingot size of the brass-chrome iron bimetals must be kept small because of the aforementioned difficulties and properties. i Where other constituents have been proposed for corrosion resisting bimetals, it has been found relatively Impossible to directly bond the metals together. For this reason, an intermediate solder layer has been used which has led to two serious disadvantages. First, the use of the solder layer decreases the corrosion -resistin'g property of the thermostat metal due to inferior bonding, and second, the solder layer decreases the strength of the metal at elevated temperatures, since the solder bond is relatively Weak. Also, solder-bonded material is difilcult to hotroll satisfactorily.

By the present invention, it is possible to accomplish a direct bond between the metals with or without an interliner of some metal, such as,

nickel, which is first plated onto the chrome steel alloy hereafter mentioned, to prevent its oxidization during heating, and they may be hot-rolled or cold-rolled in the desired manner. Their manufacture is -accordingly economical, and a highly corrosion-resisting thermostat metal is obtained According to the present invention a thei-mostatic element is provided which is corrosion-resisting per se, particularly to air, water and water vapor. thus eliminating the need for surface' plating. In addition, the present invention provides a thermostatic element made oi composite ther- .mostat metal o! the corrosion-resisting type Per cent Manganese 0.2-(16 Carbon 0.01-0.2 Chromium 12-20 Silicon. -1.5 Copper 0-1.5 Iron Remainder.

For the high expansion material an alloy of nickel, chromium and iron is employed. The composition of this alloy may be as follows:

- Per cent Nickel 16-20 Chromium 10-13 Silicon 0.2-1.0 Manganese 0.35-0.8 Carbon 0.05-0.2 Molybdenum 0-0.5 Iron Remainder.

Referring now to the drawing, a bimetallic element composed of the two alloys described above, is illustrated. Numeral 1 represents the high coefiicient of expansion iron, nickel, Chromium alloy while 3 is the low expansion iron chromium alloy.

The composite thermostat metal of which bimetal will be described as an illustrative embodiment, may be formed in the ways set forth in my co-pending application Serial Number 399398, reference to which is hereby made.

The tensile strength and other mechanical properties of the two alloys are sufficlently near to one another so that the two metals work well together and may be easily hot and cold-worked.

'This facilitates manufacture and as a result of obtaining a direct bond between the metals, a thermostat metal having a higher strength, greater activity, wider usable temperature range, longer life and better corrosion-resisting properties than the corrosion-resisting bimetals hitherto known, is obtained. Former metals allegedly designed to have these desirable properties have instead been relatively Weak, corrode relatively easily, are more diflicult to manufacture, and in genera] are not satisfactory.

As specific examples of alloys which may be advantageously employed in the present invention, the following examples are given. They are illustrative only:

Low expanson alloy No. 1

Per cent Manganese 0.2-0.6

Carbon 0.01-0.2 Chromium 12-20 Silicon .2-1.5

Copper .5-1.5

Iron -.v Remainder.

Low expansion alc No. 2

' Per cent Manganese 0.4 5 Carbon 0.05 Chromium 16 Silicon 1 Copper 1 Iron Balance now emanson aloy No. 3

Per cent Manganese 0.4 Carbon 0.05 Chromium 16-20 Iron Balance Low expanson alloy No. 4

Per cent Manganese 0.4 20 Carbon 0.05 Chromium 12-16 Silicon 1 Copper 1 Iron Balance High expamon alloy No. 1

. i Per cent Nickel 18.0 Chromium 11.5 Silicon 0.26 Manganese 0.57 Carbon 0.1 Iron Remainder.

High empansion alloy No. 2

. Per cent Nickel 18.0 Chromium 11.5

A Silicon 0.26 Manganese 0.57 Carbon 0.05 Iron Remainder.

- High ezpansion alloy No. 3 Per cent Nickel 18.0 Chromium 11.5

Silicon 0.26 Manganese 0.57 Carbon 0.1 Molybdenum 0.2-0.5 Iron Remainder.

High. expansion alloy No. 4 Pr cent Nickel 16 Chromium 10 Silicon 0.2 Manganese 0.35 Carbon 0.05 Iron Remander Attention is directed to my copending applications, Serial Nos. 28,418 and 28,419, both filed 5 May 21, 1948.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above alloys without departing from the scope of the invention, it is 'intended that all matter contained in the abovedescription shall be interpreted as illustrative and not in a limiting sense.

I claim:

l. A corrosion-'esisting thermostat metal composed of an alloy having substantially the following composition:

' Per cent Manganese 0.2-0.6 Carbon 0.01-02 Chromium e 12-20 Silicon --m 0.2-1.5 Copper 0.5-1.5 Iron Remainder and an alloy having substantially the following composition:

the surfaces of said alioys being !used together at the junction.

2. A corrosion-resisting thermostat metal composed of an alloy having substantially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 16 Silicon 1 Copper 1 Iron Remainder and an alloy having substantially the following composition:

Per cent Nickel 18 Chromium 11.5 Silicon 0,26 Manganese 0.57 Carbon 0.1 Iron Remainder the surfaces of said alloys being fused together at the junction.

3. A corrosion-resisting thermostat metal composed of an alloy having substantially the following composition:

, Per cent Manganese 0.4 Carbon 0.05 Chromium 12-16 Silicon 1 Copper 1 Iron Balance and an alloy having substantially the following composition:

the surfaces of said alloys being fised together at the junction.

4. A corrosion-resisting thermostat metal composed of an alloy having substantially the following composition:

Per cent A Manganese 0.4 Carbon 0.05 Chromium 16 Silicon 1 Copper 1 Iron Balance and an alloy having substantially the following composition:

V Per cent Nickel 18 Chronlum 11.5 Silicon 0.26 Manganese 0.57 Carbon s. 0.05 Iron Remainder the surfaces of said auoys being fused together at the junction.

5. A corrosion-resisting thermostat metal composed of an alloy having substantially'the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 16 Silicon 1 Copper 1 Iron Balance and an alloy having substantially the following composition:

. i Per cent Nickel 16 Chromium 10 Silicon 0.2

Manganese n 0.35 Carbon 0.05 Iron Remainder the surfaces of said alloys being fused together at the junction.

6. A corrosion-resisting thermostat metal composed of an alloy having substantially the following composition:

Per cent Manganese 0.4 Carbon 0.05 Chromium 12-16 Silicon 1 Copper 1 Iron Balance and an alloy having substantially the following composition:

Per cent Nickel 18 Chromium 11.5 Silicon 0.26 Manganese 0.57 Carbon 0.05 Iron Remainder the surfaces of said alloys-being fused together at the junction. 7. A corrosion-resisting thermostat metal composed of an alloy having substantially the following composition:

' Per cent Manganese 0.4 Carbon 0.05 Chromium 12-16 Silicon 1 Copper 1 Iron Balance and an alloy having substantially the following composition:

I Per cent Nickel 16 Chromium 10 Silicon 0.2 Manganese 0.35 Carbon 0.05

&401,613

the surfaces or said alloys being !used together at the junction.

8. A corroson-resisting thermostat metal composed o! an alloy having substantially the followthe surfaces'o said alloys'being !used together at the junction.

PAUL G. CHACE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,660,911 Brace Feb. 28, 1928 ,929,655 Scott Oct. 10, 1935 1,985,181 Matthews Dec. 18, 1934 2,095113? Gbbs Oct. 12, 1937 15 &146.389 Waltenberg Feb. 7, 1939 2,332,416 Waltenberg Oct; 19, 1943 2,366,178 Chace Jan. 2, 1945 FOREIGN PATENTS go Number Country Date 499350 Great Britain Jan. 24, 1939 

